Hole making or drilling generally embraces all methods for, by means of a cutting or chip-removing tool, recessing cylindrical holes in a workpiece. In addition to solid drilling, such as short-hole drilling and long-hole drilling, the present technique also includes such subsequent machining as reaming, countersinking, and different forms of finishing. Common to the different hole-making tools, to which the invention is applicable, is that a rotary motion is combined with a linear or rectilinear feeding motion. For instance, a drill can simultaneously be rotated and fed linearly during the machining of a stationary workpiece. The requisite relative motion between the tool and the workpiece may also be provided in another way, e.g., by the tool being longitudinally fed at the same time as the workpiece rotates, or vice versa. In certain operations, e.g., reaming, the tool is brought through a pre-drilled hole without being intended to be brought back out of the same. In other operations, the tool is intended to be brought into as well as out of the hole. However, also in the first case, the need of retracting the tool through the machined hole may arise, for instance if one or more cutting inserts become damaged or come loose from the tool, or that the driving machine facility stops. Irrespective of whether a retraction of the tool from the hole is intentional or unintentional, problems may arise so far that the surrounding hole surface risks being damaged by peripherally situated cutting inserts. At times, difficulties when removing the tool from the hole also occur. Damage to the hole surface is generally undesired. In the worst case, the same may cause rejections of expensive components.
In U.S. Pat. Nos. 8,845,243 and 8,684,640, there are disclosed two hole-making tools in the form of reaming tools, the basic body and cutting inserts of which are formed with a pair of co-operatable male- and female-like securing means, which do not contact each other as long as the cutting insert, due to the axially acting cutting forces, is held in close contact pressed against the axial support surface in an appurtenant seat in the basic body of the tool, but which are activated as soon as the cutting insert, due to a reversal of the axial direction of motion of the tool, is moved apart from the axial support surface. More precisely, the securing means are formed in such a way that a gap or play of 0.1-0.2 mm is maintained between the same as long as the cutting insert is reliably fixed in the seat. If the tool, after a mishap has occurred, needs to be removed from the machined hole, the securing means are activated during the extremely short time that the cutting insert moves axially 0.1-0.2 mm, wherein the securing means relieve the tightening member, e.g., a screw, that clamps the cutting insert in the seat. However, the securing means of the disclosed tool are only intended to counteract axial displacement of the cutting insert out of the seat, but not to prevent the cutting insert from moving in the direction radially out of the seat. Even if the securing means generally guarantee that the cutting insert remains in the seat, the same do not prevent or counteract the cutting insert from moving radially outward; which may give cause scratches or other damage in the generated hole surface.